1. Field of the Invention
This invention relates to a process for sorting mixtures of discarded, unsorted waste objects such as films, cups, bottles, and foams made of plastic, carton packaging made of composites for liquid food products, aluminum foil packages, and other unsorted waste objects. An aspect of this process relates to identification of various types of objects, followed by a sorting step. Another aspect of this process relates to the use of a form of radiation to aid in the identification step. Still another aspect of this invention relates to an apparatus for sorting out mixtures of waste objects. An aspect of this device relates to the use of a radiation source.
2. Description of the Prior Art
The recovery of re-usable materials from waste is becoming increasingly important in industry as well as in households. In this context, special mention should be made of the German Dual System, according to which packaging materials and packaging products are collected separately in special bins in households; participating businesses guarantee that they will accept all of the material collected and that they will re-use this material.
This collection results in a mixture of materials such as films, cups, bottles and foams made of plastic, carton packaging made of composites for liquid food products and metal packaging materials made, for example, of tinfoil or aluminum.
When it comes to recycling, the more completely sorted the recovered material, the higher the quality of the products made of such materials. Therefore, further development of the sorting technology is a decisive factor for the successful implementation of the Dual System.
Even though intensive development work is under way in the realm of sorting technology, it is not yet possible to sort out, for example, the individual components from a mixture of chemically related plastics such as polyethylene and polypropylene. Another problem involves the fillers and additives contained in the plastics, since they cause substantial changes in the properties of the pure plastic.
A known example from the state of the art is the AKW process, according to which heavy plastics such as polystyrene and polyvinyl chloride are separated in hydrocyclones from the light-weight fraction consisting of polyethylene and polypropylene (AKW-Apparate+Verfahren GmbH, address: Georg-Schiffer-Strasse 70, 8452 Hirschau, Germany).